Interplay between Klebsiella pneumoniae producing KPC-31 and KPC-3 under treatment with high dosage meropenem: a case report.

The objective was to study ceftazidime-avibactam resistant and susceptible Klebsiella pneumoniae isolated from a patient admitted to the Policlinico Umberto I of Rome for SARS-CoV2. Data on the evolution of patient's conditions, antimicrobial therapies, and microbiological data were collected. Whole-genome sequencing performed by Illumina and Nanopore sequencing methods were used to type the strains. During the hospitalization, a SARS-CoV2-infected patient was colonized by a KPC-producing K. pneumoniae strain and empirically treated with ceftazidime-avibactam (CZA) when presenting spiking fever symptoms. Successively, ST2502 CZA-resistant strain producing the KPC-31 variant gave a pulmonary infection to the patient. The infection was treated with high doses of meropenem. The KPC-31-producing strain disappeared but the patient remained colonized by a KPC-3-producing K. pneumoniae strain. An interplay between highly conserved KPC-31- and KPC-3-producing ST2502 strains occurred in the SARS-CoV2 patient during the hospitalization, selected by CZA and carbapenem treatments, respectively.